Noble gas isotopic variations and geological implication of Longmaxi shale gas in Sichuan Basin, China

Cao, Chunwei; Zhang, Mingjie; Tang, Qingyan; Yang, Yang; Lv, Zonggang; Zhang, Tongwei; Chen, Chang; Yang, Hui; Li, Liwu

doi:10.1016/j.marpetgeo.2017.01.022

Cited by 46 publications

(36 citation statements)

References 53 publications

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“…The purified gases were then absorbed in a cryogenic trap at the temperature of 8 degree K for 20 min. Then He and Ar were released under 15 degree K and 100 degree K respectively and introduced into the Noblesse SFT noble gas mass spectrometer separately for He and Ar concentrations and isotopic ratios measurement (Cao et al, 2018).…”

Section: Methodsmentioning

confidence: 99%

Granite is an Effective Helium Source Rock: Insights from the Helium Generation and Release Characteristics in Granites from the North Qinling Orogen, China

Wen

Zhao

et al. 2020

Acta Geologica Sinica (Eng)

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Global helium (He) shortage is a challenging problem; however, the types of helium source rock and the mechanisms of He generation and release therein remain still poorly understood. In this study, in order to evaluate the potential of granite as an effective helium source rock, we collected granitic samples from the North Qinling Orogen, Central China, in the south of the helium‐rich Weihe Basin. The helium generation and release behaviors in granite were studied through analysis of U and Th concentrations, EMPA images, and He and Ar concentrations and isotopic ratios extracted by crushing and stepwise heating. The results indicate that Ar has a better retention and a lower mobility than He. 3He/4He ratios released by crushing and stepwise heating are 0.016–0.056 RA and 0.003–0.572 RA, respectively, where RA is the atmospheric 3He/4He of 1.4×10‐6, reflecting a crustal and radiogenic source. Helium concentrations extracted by the two ways are 0.13–0.95 ucm3 STP/g and 7.82–115.62 ucm3 STP/g, respectively, suggesting that matrix‐sited He accounts for more than 98% of total helium preserved in granite. In addition, the total generated He amounts in granites are calculated based on the measured U and Th concentrations in granitic samples. Dividing the preserved He quantities by the generated He amounts, it turned out that less than 10% of He produced since the formation of the granite is preserved in the rock over geological time, suggesting that more than 90% generated He can be transferred to the Weihe Basin. Temperature and fracture are the two critical factors controlling He release. Based on the relationship between He diffusivity of granites and temperature and the He closure temperatures of a variety of U‐ and Th‐rich minerals (27–250°C), we estimate that He can be partially released out of granite at the depths <400 m and totally released at the depths >7800 m. Fractures provide effective transfer of free He from deep source rocks to shallow reservoirs. Finally, a model on granite as an effective helium source rock is established. We suggest exploring He resources in hydrocarbon basins with granitic basement (or adjacent to granite bodies), high geothermal field, and young active fractures.

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Section: Methodsmentioning

confidence: 99%

Granite is an Effective Helium Source Rock: Insights from the Helium Generation and Release Characteristics in Granites from the North Qinling Orogen, China

Wen

Zhao

et al. 2020

Acta Geologica Sinica (Eng)

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“…Finally, the measured data were calculated after measuring the voltage ratio of relevant ions from both the standard sample and the sample obtained. The extraction and analysis methods of volatiles are described in detail by [10,22,26].…”

Section: He Nementioning

confidence: 99%

“…The mass interferences at m/z = 22 of ( 20 Ne) + and ( 22 Ne) + from ( 40 Ar) 2+ and ( 12 C 16 O 2 ) 2+ were corrected using CO 2+ /CO 2 + = 0 004. The details of Ne and data correction procedures were described in detail in [22,26,27].…”

Section: He Nementioning

confidence: 99%

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The Petrogenesis of the Permian Podong Ultramafic Intrusion in the Tarim Craton, Western China: Constraints from C-He-Ne-Ar Isotopes

Zhang

Feng

et al. 2019

Geofluids

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The Podong Permian ultramafic intrusion is only one ultramafic intrusion with massif Ni-Cu sulfide mineralization in the Pobei layered mafic-ultramafic complex, western China. It is obviously different in sulfide mineralization from the nearby coeval Poyi ultramafic intrusion with the largest disseminated Ni-Cu sulfide mineralization and mantle plume contribution (Zhang et al., 2017). The type and addition mechanism of the confirmed crustal contaminations and possible mantle plume involved in the intrusion formation require evidences from carbon and noble gas isotopic compositions. In the present study, we have measured C, He, Ne, and Ar isotopic compositions of volatiles from magmatic minerals in the Podong ultramafic intrusion. The results show that olivine, pyroxene, and plagioclase minerals in the Podong intrusion have variable δ13C of CO2 (-24.5‰ to -3.2‰). The CH4, C2H6, C3H8, and C4H10 hydrocarbon gases show normal or partial reversal distribution patterns of carbon isotope with carbon number and light δ13C1 value of CH4, indicating the hydrocarbon gases of biogenic origin. The δ13C of CO2 and CH4 suggested the magmatic volatile of the mantle mixed with the volatiles of thermogenic and crustal origins. Carbon and noble gas isotopes indicated that the Podong intrusion could have a different petrogenesis from the Poyi ultramafic intrusion. Two types of contaminated crustal materials can be identified as crustal fluids from subducted altered oceanic crust (AOC) in the lithospheric mantle source and a part of the siliceous crust. The carbon isotopes for different minerals show that magma spent some time crystallizing in a magma chamber during which assimilation of crustal material occurred. Subduction-devolatilization of altered oceanic crust could be the best mechanism that transported large proportion of ASF (air-saturated fluid) and crustal components into the mantle source. The mantle plume existing beneath the Poyi intrusion could provide less contribution of real materials of silicate and fluid components.

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“…The releasing temperature of each noble gas (He, Ne, Ar, Kr, or Xe) is not the same in different studies due to the equipment condition.31,59,62-66,89-91 4 He,20 Ne, 40 Ar and 36 Ar are generally measured on a Faraday cup. Other noble gas isotopes are usually determined on the electron multiplier in ion counting mode 73,91.…”

mentioning

confidence: 99%

The Use of Noble Gas Isotopes in Detecting Methane Contamination of Groundwater in Shale Gas Development Areas: An Overview of Technology and Methods

Cao

et al. 2020

ANAL. SCI.

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Groundwater contamination by stray gas (mainly methane) in areas of shale gas development has captured the publics', political and scientific attention. However, sources and potential mechanisms of groundwater contamination are still debated. Noble gases can provide useful information on fluid migration for discerning scale, conditions, and physical mechanisms. In this study, details about analytical technology and theoretical approach of noble gases in tracing groundwater contaminations are presented. In addition, applications of noble gases isotopes for determining contamination sources and potential pathways are explored and reviewed. Recent developments are discussed and highlighted focusing on new utilities of noble gas isotope parameters in evaluating groundwater contamination. Some usages of indicators (4 He/ 20 Ne, CH 4 / 36 Ar, 4 He/CH 4 , etc.) are discussed through specific research articles. And it is a new trend to make comprehensive use of multiple geochemical parameters to determine the occurrence, source, and process of methane pollution in groundwater.

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Noble gas isotopic variations and geological implication of Longmaxi shale gas in Sichuan Basin, China

Cited by 46 publications

References 53 publications

Granite is an Effective Helium Source Rock: Insights from the Helium Generation and Release Characteristics in Granites from the North Qinling Orogen, China

Granite is an Effective Helium Source Rock: Insights from the Helium Generation and Release Characteristics in Granites from the North Qinling Orogen, China

The Petrogenesis of the Permian Podong Ultramafic Intrusion in the Tarim Craton, Western China: Constraints from C-He-Ne-Ar Isotopes

The Use of Noble Gas Isotopes in Detecting Methane Contamination of Groundwater in Shale Gas Development Areas: An Overview of Technology and Methods

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